The invention is related with the chemical synthesis for increase the growth rate in marketable fish and crustacean. The synthesis of peptide analogs of Leu and Met enkephalins was reported and showed that they stimulated growth hormone (GH) release in animals (Bowers C, Momany, G, Reynolds G and A. Hong. 1984. On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the Pituitary to specifically release growth hormone. Endocrinology. 114: 1537-45).
Studies to investigate structure-activity relationships of GH releasing peptides (GHRPs) continued and let to the identification of GHRP-6 (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) (SEQ. ID. NO.: 1), who has been demonstrated to be an extremely potent and safe GH secretagogue (GHS) in animals, including humans, however no previous report has been published using this compound in aquatic organisms.
We demonstrated as a novel fact, taking into account the lack of evidence crustaceans of the signal cascade to stimulate growth (hypothalamus—pituitary gland—target organ), that the peptide GHRP-6 alone is able to exert a similar biological function in crustaceans than in mammals.
Fresh water fish is the principal production in aquaculture, nevertheless in the last decade the increasing of culture of marine algae, mollusks and crustaceans had been significantly. The improving knowledge of the genetic, reproduction, nutrition and the physiology of the organisms to cultivate is the first step to improve the aquaculture production (Gómez-Chiarri M, Smith G J, de la Fuente J and Powers D A. 1998 Gene transfer in shellfish and algae. In de la Fuente J and Castro F O, editors. Gene transfer in aquatic organisms. Austin, Tex.: R G Landes Company and Germany: Springer Verlag; p. 107-125).
The study of the molecular characteristic from the hormone and peptides involved in the growth mechanism in the marketable fish and crustacean species is very important to use in the improving the aquaculture.
One example to understand that is the use of gonadotropin release hormone (GnRH) and the antagonist of the dopamine receptor used by Silverstein et al., in 1999 (Silverstein J T., Bosworth B G. and Wolters W R. 1999. Evaluation of dual injection of LHRHa and the dopamine receptor antagonist pimozide in cage spawning of channel catfish Ictalarus punctatus. Journal of the World Aquaculture Society. Vol. 30, No. 2, June, 263-268) for the regulation and induction of reproduction in catfish (Ictalarus punctatus). This species has high importance in world aquaculture.
Hashizunme et al., reported in 1997 (Hashizume T., Sasaki M., Tauchi S. and Masuda H. 1997. The effect of new growth Hormone-releasing peptide (KP 102) on the release of growth hormone in goats. Animal Science and Technology. Vol. 68, No. 3, March, 247-256) the use of a synthetic peptides for the increase of the productivity in animal farms. They demonstrated the induction of growth hormone in goat by injection with a novel growth hormone release synthetic peptide
Insulin had been administrate to fish orally and demonstrated changes in signal of receptor and hormones involved in carp adaptation to different temperatures (Vera M I., Romero F., Figueroa J., Amthauer R., Leon G., Villanueva and Krauskopf M. 1993. Oral administration of insulin in winter-acclimatized carp (Cyprinus carpio) induces hepatic ultrastructural changes. Comp. Biochem. Physiol. Vol. 106A, No. 4, 677-682)
In mammals had been tested synthetic variants of the growth hormone release peptide by Patchett et al., in 1995. They probed the peptide MK-0677, designated as potent oral activator of the GH in dogs without effect in the tyrosine and prolactin levels after application (Patchett A A., Nargund R P., Tata J R., Chen M H., Barakat K J., Johnston D B R., Cheng K., Chan W W S., Butler B., Hickey G., Jacks T., Schleim K., Pong S S., Chaung L Y P., Chen H Y., Frazier E., Leung K H., Chiu S H L. and Smith R G. 1995. Proc. Natl. Acad. Sci. USA. Vol. 92, 7001-7005)
Other application of the growth hormone release hormone had been developed in cattle to increase the milk production, taking into account the stimulation in milk production produced by the increased level of the circulating GH (Soliman E B., Hashizume T., Ohashi S. and Kanematsu S. 1997. Effects of Growth hormone (GH)-releasing hormone and its analogs on GH secretion from cultured adenohypophysial cells in cattle. Domestic animal endocrinology. Vol. 14(1), 39-46)
There are not previous reports of the use of GHRP-6 in fish or crustacean. The use of GHRP-6 in fish and crustacean to stimulate growth, improve the larvae quality, and increase the defense against pathogen agents, the dry weight, the protein concentration and the RNA in muscle of fish and crustaceans reported in this document comprise a solution for improve the productivity in the aquatic organisms culture.
There are preliminary results in the genetic breeding of some shrimp species like Penaeus japonicus and Litopenaeus vanname but these are not enough because the lack of knowledge about the genetic and biochemistry of these organisms (Benzie, J. A. H., 1998. Penaeid genetics and biotechnology. Aquaculture 164, 23-47 and Fjalestadl, K. T., Carr, W. H., Lotz, J. L., Sweeney, J. N., 1999. Genetic variation and selection response in body weight and diseases resistance in the Pacific White Shrimp Penaeus Õannamei. Aqucculture 173, 10, Abstract only). It is very important to apply the biotechnology, molecular biology, genetic engineering and biochemistry to the culture of shrimp to improve the productivity (Bachere, E., Mialhe, E., Noel, D., Boulo, V., Morvan, A., Rodriguez, J. (1995) Knowledge and research prospects in marine mollusc and crustacean immunology. Aquaculture. 132, 17-32).
This invention support that the GHRP-6 alone is able to stimulate growth, improve the larvae quality, and increase the defense against pathogen agents, the dry weight, the protein concentration and the RNA in muscle of fish and crustaceans.